A floppy-eared, innocent-looking breed may be one of the world’s most aggressive dogs, according to a new study that found English cocker spaniels tend to be more hostile than other breeds.The discovery adds to the mounting evidence that aggressiveness is an inherited characteristic, suggesting that genes and breeding practices can both help determine how a dog will behave.

“In our country and according to our database, the English cocker spaniel is the breed that shows more aggression problems,” lead author Marta Amat told Discovery News.Amat, a researcher in the School of Veterinary Medicine at the Autonomous University of Barcelona, and her colleagues analyzed 1,040 cases of canine aggression brought to a nearby veterinary teaching hospital from 1998 to 2006. Of those cases, the majority of cases were attributed to English cocker spaniels, Rottweilers, Boxers, Yorkshire terriers and German shepherds.More

Personality might play a big role in how long dogs live. Live fast die young might also apply to dogs, a study in the June issue of The American Naturalist suggests.Vincent Careau, of the University of Sherbrooke in Quebec, Canada, and his colleagues came to that conclusion by comparing numerous dog breeds based on their personalities. For example, poodles are ranked as 29 percent more docile than boxers, and Careau’s team found that poodles are four times more likely than boxers to live past age 10.

Beyond simply looking at aggressiveness, the researchers also found that the most obedient breeds, such as German Shepherds, Poodles, and Bichon Frises, live considerably longer than hard-to-train dogs such as Beagles and Pomeranians. Careau used personality data based on a 1995 psychology study that ranked dog personalities and also compared dogs of similar size.More